403 Forbidden error when trying to view .module and other files

Site Environment: Pantheon, running D7 site on nginx server
Local Environment: Kalabox with cloned instance of Pantheon server site, so config should be same as on server.

On my local machine, all .info files can be diffed, but when clicking .module, .inc, .js files, the error occurs. I've granted permissions to all roles for the module, but no change. When running this on the Pantheon servers, it seems I can't access any of the files. I'm assuming this is an nginx issue, but when it's not possible to alter the server config, isn't there a way to get this to work?